Image Sharpening Double Control
The UnSharp Mask (also known as USM) filter boosts the image's perceived sharpness (high frequency detail) by means of artificial Dark and Light Halos, created around borders. Since its first appearance (Photoshop 1.0, 1990) USM hasn't changed: you're allowed to control Radius (how thick halos are) and Amount (how strong halos are), besides Threshold.
Double USM doubles your sharpening control: you can set a Radius, an Amount and a Threshold for Dark Halos, and different ones for Light Halos. As Color-Correction expert Dan Margulis has demonstrated, Light Halos tend to be visually more offending and need to be toned down - both in their intensity (Amount) and in their thickness (Radius).
A heavy handed pre-press default USM is 500-1 (Amount-Radius), that you can always tone down with Layer's opacity. Double USM gives a more natural effect with (400-1.5) for Dark Halos and (250-0.7) for Light Halos - about half intensity and half thickness.
Also known as High-Radius, Low Amount: used to give shape and sort of a 3D look. A starting point could be (50-50) for Dark Halos and (30-30) for Light Halos. As you see, the Radii are unusually high, while Amounts are below the values you would expect.
With Double USM nothing prevents you from experimenting: a creative sharpening might imply a Standard USM for Dark Halos (say, 400-1.5) and HiRaLoAm for Light Halos (say, 30-50) in order to get the best of both worlds!
Create and apply your own Sharpening Presets! Mind you, when it comes to Sharpening there are no perfect receipts nor absolute values: it always depends on the image's resolution, subject, and eventually on your own taste!
Everything you need to know about Double USM 2 in six minutes of weird fun. Believe me.
Compact documentation to introduce the Interface, with easy sharpening examples.
What's the UnSharp Mask filter all about and what's wrong with it.
Professional images case study by Double USM author Davide Barranca.
Double USM (2.0.0)
Multiplatform License $34.95Buy here Photoshop CC → CC2017
(Mac & Win)Current Version: 2.0.0